Here's why:
* Morphemes are the building blocks of words. They carry meaning, and cannot be broken down into smaller meaningful units.
* Phonemes are the smallest units of sound in a language, but they don't carry meaning on their own.
* Syllables are units of pronunciation, and while they can be meaningful, they are not the smallest meaningful unit.
Examples of morphemes:
* "un-" (prefix meaning "not"): unhappy, undo
* "-ing" (suffix meaning "present participle"): running, jumping
* "cat" (root word meaning "feline animal"): cats, catnip
Let me know if you have any other questions!